SYNTHETIC, NUCLEAR-MAGNETIC-RESONANCE AND X-RAY CRYSTALLOGRAPHIC STUDIES OF CONFORMATIONS OF POLYORGANOPHOSPHORUS COMPOUNDS

Addition reactions between ERH2 (E = P or As; R = Ph, CH2CH2CN, Bu or C6H2But3-2,4,6) and (Ph2P)2C=CH2 or (Ph2P)2C=CHR' (R' = H or Me) yield the triphosphines (Ph2P)2CHCHR'ERH and the pentaphosphines [(Ph2P)2CHCH2]2ER and (Ph2P)2CHCH(Me)P(Ph)CH2CH(PPh2)2. The two- and three-bond P-31-P-31 nuclear spin-spin coupling constants in these vary substantially with the bulk of substituents on or near phosphorus, probably as a result of conformational differences. The structures of (Ph2P)2CHCH2PHPh, (Ph2P)2PCHCH2PH(C6H2But3-2,4,6) and [(Ph2P)2CHCH2]2PPh have been determined by X-ray diffraction and suggest that each of these species adopts a conformation in solution that is very similar to that found in the solid state.